Copolymers of pivalolactone and isoprene or butadiene

ABSTRACT

Disclosed herein are new, specifically modified, copolymers of pivalolactone with isoprene and/or butadiene. Also disclosed is a process for making copolymers comprising (1) polymerizing the diene with a lithium initiator and, optionally, metallating the resulting lithiopolydiene with an alkyllithium, (2) carboxylating the resulting polylithiopolydiene by reaction with carbon dioxide, (3) reacting the polymeric lithium carboxylate with tetraalkylammonium hydroxide or halide and (4) reacting the tetraalkylammonium salt with pivalolactone.

United States Patent [1 1 Foss [ Sept. 23, 1975 COPOLYMERS OFPIVALOLACTONE AND ISOPRENE OR BUTADIENE [75] Inventor: Robert Paul Foss,l-lockessin, Del.

[73] Assignee: E. I. Du Pont de Nemours and Company, Wilmington, Del.

[22] Filed: Nov. 6, 1973 [21] Appl. No.: 413,367

Related U.S. Application Data [60] Division of Ser. No. 324,502, Jan.17, 1973, Pat. No, 3,821,331, which is a continuation-in-part of Ser.No. 227,258, Feb. 17, 1972, abandoned.

[52] U.S. Cl. 260/887; 161/231; 260/879 [51] Int. Cl. C08L 9/00; C08L13/00 [58] Field of Search 260/879, 887

[56] References Cited UNITED STATES PATENTS 6/1964 Uraneck et al.260/887 12/1968 King 260/857 3,557,255- 1/1971 Sharkey 260/879 FOREIGNPATENTS OR APPLICATIONS 7,003,074 9/1971 Netherlands 260/887 PrimaryExaminer-John C. Bleutge Assistant Examiner-J. Ziegler [5 7] ABSTRACT 10Claims, No Drawings COPOLYMERS OF PIVALOLACTONE AND ISOPRENE ORBUTADIENE CROSS REFERENCE TO RELATED APPLICATIONS This application is adivision of my copending application Ser. No. 324,502. filed Jan. 17.1973, now U.S. Pat. No. 3,821,331, which is in turn acontinuation-inpart of my copending application Ser. No. 227.258, filedFeb. I7, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to specifically modified copolymers derived from pivalolactoneand isoprene and/or butadienc.

2. Description of the Prior Art ABA typc copolymers are taught inSharkey, U.S. Pat. No. 3,557,255, wherein the A blocks arepolypivalolactone and the B block is polyisoprene or polybutadiene.Copolymers taught herein are structurally different from such prior artcopolymers in that they contain a unit between A and B blocks. Processesare nonanalo in several aspects including, inter alia: it begins with apreformed nonlithiated polymer that must first be dissolved; thedissolved polymer, if not intrinsically carboxylated, is carboxylated byreaction with a carboxylic acid or anhydride.

SUMMARY OF THE INVENTION The novel products of this invention includecopolymers (A):

(pivalolaclonc-) OC-(-dicnc C-O-(pivalolactone) l m n wherein l and nare between about to 4000. and m is between about 25 to 25,000.Preferred values for l and n are about to 200, and for in about 100 to5.000. Also included are novel copolymers (B):

' (pivalolactouefi OC-- dienc)- CO(pi\'alolactone) l m n (pivalolactonc)wherein I. n and I; are between about 5 to 4000. m is between about to25.000 and x is from about I to 350. Preferred values for I. n and k areabout 15 to 200. for m about 100 to 5.000 and for about g l to 50.

Included also are copolymers (C):

(pivalolactonc+ O-C( dic|ne-) R i 0 (pivakilactonc) wherein I and k arebetween about 5 to 4000. m" is between about 25 to 25.000, .r' is fromabout 1 to 1 attached to the polydiene substrate in copolymers (B) and(C). It should be understood that, in copolymers (B) and (C), there isno more than one sidechain polypivalolactone segment forcach diene unit.

The molecular weights of the polypivalolactone segments in copolymers(A), (B) and (C) vary between about 500 to 400,000, and the molecularweights of the polydiene segments vary betweenabout 1300 to 1,700,000.Butadiene and isoprene are the contemplated dienes.

PROCESS The novel process taught herein comprises what is preferably,but not necessarily, a so-called one-pot or continuous process. Thereaction process proceeds according to the sequential relationship setout hereafter. The contemplated process is operable to produce a broaderrange of products than are specifically taught herein. For instance,copolymer types (A), (B) and (C) can be made with k, l, m, n, x and Rvalues significantly broader than disclosed. Those skilled in the art,upon reading this disclosure, will understand how to operate the novelprocess to obtain a wider array of type (A), (B) and (C) copolymers thanare specifically set out.

Step 1(a) diene monomer lithium initiator in hydrocarbon"solven'tlithiopolydiene, and (b, optional')f-lithiopolydiene alkyllithiumpolylithi- Topolydiene; The=lithiopolydiene of Step 1(a) may be ana-monolithio or an a,w-dilithiopolydiene. The polylithiopoly'dieneproduct of Step l(b) is a multilithiated polydiene containing at leasttwo lithio groups and generally more. e.g. up to about 350 randomlylocated lithio groups of which no more than two are cnd groups. Thelithium initiator is selected from the group consisting of monolithiocompounds which propagate formation of a-monolithiopolydienes, anddilithio compounds which propogate formation of cum-dilithiopolydienes.When the lithium initiator is a dilithio compound and Step 1(12) isomitted. copolymer A is produced. When the lithium initiator is adilithio compound and Step 1(1)) is included. copolymer B is produced.When the lithium initiator is a monolithio compound, Step l(b) must beincluded and copolymer e is produced.

Step 1(a) is primarily a diene polymerization step and Step 1(b) issolely a metallation (lithiation) step whereby the alkyllithium(complexed with a diamine as will be more fully discussed hereafter)acts to lithiate allylic carbons in the initial lithiopolydiene.

Step 2 polyiithiopolydiene CO; lithium salt of polydienepolycarboxylicacid.

DETAILS OF THE INVENTION General Process Parameters Step 1 t The dienepolymerization (Step la) is carried out in a nonpolar medium in order toobtain a center block of sufficiently high 1.4-content to give goodrubber properties in the final product. However, when B or C are thedesired copolymers. aromatic-type solvents such as benzene and toluenecannot be used since they interfere with the metallation reaction ofStep 1(1)). The rate of diene polymerization is primarily dependent uponthe polymerization temperature. The preferred conditions include thetemperature range from to 100C. A temperature of about 60C. isespecially preferred for best results. Under these conditions polydicnesof narrow molecular weight range are obtained.

Operable monolithio initiators are alkyllithiums and includemethyllithium, ethyllithium, n-butyllithium. sec-butyllithium.octyllithium and dodecyllithium. The butyllithiums are preferred.

Operable dilithio initiators include: (1) dilithio a-methylstyreneoligomer (Karoly, ACS Polymer Preprints. 10, No. 2, September 1969); (2)l.3-bis( llithio-3methylpentyl)benzene. made by addition ofsec-butyllithium to m-divinylbenzene (KamienskLPolymer Preprints. FirstAkron Summit Polymer Conference. Symposium on Anionic Polymerization.-University of Akron. p.24. June 18-19. 1970), soldundcr the trademarkDiLi-3, registered in the name of Lithium Corporation of America; (3)dilithio isoprene v oligomers, (dilithio-isoprene oligomers inbenzenetriethylamine solution), see Product Bulletin v 191',.Lith-' iumCorporation of America; (4) 1,4-dilithio.-; 1,l 4.4- tetraphenylbutaneprepared by reacting lithium with l.l-diphenyletliylene (Fctters andMorton. Macromolecules. 2. 45-3 19.69); and (5) l.3-bis(l-lithio-lmethyl-'l-alkylethyl )benzenc wherein R is an alkyl. preparedby the addition of m-diisopropcnylbenzene The steric hindrance inducedby the l-methyl groups apparently precludes the addition of furthermdiisopropenyl benzene molecules with the concomitant possibilityofinitiatorswith several rather than two lith ium atoms. These preferredinitiators with exactly two lithium atoms can then produce purecam-dilithiopolydienes free of'undesiredbranch chains and permits thedevelopment of block copolymers with no sidechains attached to theinitiator molecules themselves.

Thus. in general. initiator types (2) and (5), especially the latter.represent the preferred initiators. Moreover, it is expected that otheruseful initiators would include compounds similar to the two preferredtypes (2) and (5) that can be described more generally as solutions ofalpha-lithio substituted dialkylbenzenes and dialkylbenzene oligomers inhexane-triethylamine solution.

In Step l it is important to perform Steps 1(a) and 1(b) separately. Thediamine complexing agent necessarily used in Step 1(h) should not bepresent in Step 1(a) since it can promote a competing side reactioninvolving the diene monomer and the alkyllithium or the lithiopolydieneproduct which results in formation of polydiene with undesirable l,2 or3,4-microstructure. Therefore. any diamine complexing agent employed forStep 1(1)) should be added'only after completion or near completionofthediene polymerization. After substantially all of the diene ispolymerized, the diamine can be added separately. or. in any order. withadditional alkyllithium, or as a preformed complex.

Operable alkyllithium lithiating agents for Step 1(b) include thoselisted above as monolithio initiators. The alkyllithium and diaminecomplexing agent can be added separately or together as a mixture.Thislis done after all diene has been consumed in Step 1(a) in order topreserve the high 1,4-microstructure. The mixture is then allowed toreact for up to 2 hours or longer at about 60C. to effect metallation,

when copolymer B or C is desired. the alkyllithium for Step 1(h) isadded in an amount equivalent to the number of polypivalolactonesidechains desired. exclusive of polypivalolactone end groups.

The diamine complexing agent is usually added in an excess amount thatfor good results may even be as high as about 2.2 equivalents based onthe total lithium employed in Steps 1(a) and l(h)'. Operable complexingamines include N,N,N,N-tetramethylethylenediamine (TMEDA),N,N,N',N'-tetraethylethylenediamine, N,- N,N,N'-tetrabutyl-l,4-butylenediami'ne and the like. Step 2 v I Carbon dioxide can be addedas a solid, gas, or preferably, in solution in a suitable solvent suchas tetrahydrofuran (THF). THF is saturated with carbon dioxide (CO bybubbling the gas into it under slight pressure. This CO saturatedsolution is then passed into the polyanionic polymer mixture underefficient stirring between room temperature and the temperature employedin Step 1. Alternatively, the polylithiopolydiene solution from Step Imay be transferred into the CO saturated THF with vigorous stirring.Such transfer is preferably effected by applying argon pressure to forcethe solution of polylithiopolydiene through glass or steel tubing fromthe first closed reactor to the second. After allowing sufficient timefor the carboxylation to be completed, the mixture can be heated todrive off excess CO This can also be accomplished by bubbling nitrogenthrough the mixture or mild evacuation. In this step a small amount ofpure THF can be added to the polydiene polyanionic system to reduce theviscosity, if necessary. N,N,N',N-Tetramethylethylenediamine may also beused to accomplish the task of reducing viscosity. The reduction ofviscosity is desirable in that it allows more efficient mixing of carbondioxide. Step 3 This process step involves exchange of tetraalkylamvmonium cations for lithium cations in the polydienepolycarboxylate. Thereaction can be illustrated by the equation compounds aretetrabutylammonium hydroxide and tetrabutylammonium chloride, althoughother salts than the chloride can be used.

The reaction proceeds at temperatures down to about 0C. and ispreferably conducted-"in the range from room temperature to about 60C.although higher temperatures can be employed. It is surprising thatunder these conditions the exchange of cations in the above equation isessentially complete. Instead. an equilibrium condition and-theexistence of a significant proportion of unchanged R NX in the reactionsystem would ordinarily be expected. This is an important aspect sincein the following Step 4, when ivalolactone (PVL) is present. unchangedR' NX in the mixture could initiate undesirable formation of PVLhomopolymer.

Although the R NX compound could be added in excess. it might thenbecome necessary to isolate and purify the polymeric quaternary ammoniumsalt to remove excess or unreacted R ,NX before addition ofpivalolactone. Otherwise, free PVL homopolymer could be formed and couldinterfere with product properties or, at least, raise the problem of itsremoval. Excess or unreacted R NX can be removed by precipitation in anonsolvent for the polymer. steam stripping.

etc.

To eliminate the necessity for R' NX removal. it is preferred to use nomore than an equivalent amount of R' NX, based on total lithium. It ismost preferred to employ less than an equivalent amount of RQNX. It hasbeen found, in fact, that as little as 20% or less of an equivalentamount of R' NX is sufficient to achieve the desired result in thefollowing Step 4.

Step 4 Pivalolactone monomer is added to the tetraalkyl ammonium saltproduct of Step 3 and polymerized at a temperature between about 0 to C.Room temperature is preferred. The polymerization is carried out in anonpolar solvent such as cyclohexane. benzene, or toluene or in a polarsolvent such as tetrahydrofuran or ethylene glycol dimethyl ether or ina combination of polar and nonpolar solvents. The use of polar solventsalone or in combination with nonpolar solvents is preferred since suchmedia provide less viscous, more readily stirrable reaction mixtures.

Surprisingly, when less than the equivalent amount of R NX is used,after the first step of initiation of PVL polymerization has occurredand the quaternary ammonium ion becomes transferred to the carboxylate(anionic) end of a growing polypivalolactone chain there takes place anapparently very rapid transfer between such quaternary ammonium cationsand lithium cations at all carboxylate sites. The end result is anessentially equivalent propagation of growing polypivalolactone chainsat all carboxylate sites on the polydiene polycarboxylic base. Thiseffect is illustrated in Examples 5, 6 and 7.

Steps 3 and 4 can be combined and if combined the PVL monomer can beadded before, during or after addition of the R NX compound. if thelatter is used in no more than an equivalent amount, calculated on thelithium in the lithium salt of the polydienepolycarboxylic acid. Byadding PVL beforehand a desirable blending of PVL into the mixture canbe achieved before its polymerization is initiated by the quaternaryammonium polydienepolycarboxylate. If the PVL is first dissolved in THFand then added, there is an added advantage in reduced tendency forprecipitation of the polydiene. 1

Temperature is quite important should it be desired to combin Steps 3and 4. Temperatures should be kept at about 50C. or below and preferablybelow 30C., to avoid competing homopolypivalolaetone formation by thequaternary ammonium hydroxide or halide. Under these mild conditions thereaction of the quaternary ammonium compound with the lithium salt ofthe polydienepolycarboxylic acid (the reaction of Step 3 and thereaction of the quaternary ammonium salt formed thereby withpivalolactone are much more rapid than the reaction of pivalolactonewith quaternary ammonium compound. Therefore. pivalolactone can be addedto the lithium salt of the polydicnepolycarboxylic acid before or afterthe Step 3 addition of the quaternary ammonium compound thereto.

The novel copolymers disclosed herein are useful for various purposes aswill be evident to those skilled in the art. As articles of manufacture,uses include elastic fibers. extensible films. general purpose rubbers(tires). high impact strength plastics. injection molded articles. andthe like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following Examples aremeant to illustrate but not to limit the invention. The Examples arefollowed by a discussion of the surprising properties displayed by thesenovel copolymers. In each of the Examples, the making of thecorresponding butadiene-containing copolymer can be effected bysubstitution of equivalent amounts of butadiene for isoprene.

EXAMPLE 1 Pivalolaetone/Isoprene/Pivalolactone Copolymer (A) Step 1(a)Polyisoprene Dilithio a-Methylstyrene Oligomer (Initiator) A small (59mmX 28 mm) dry glass vial containing a magnetic stirring bar was loadedwith 0.15 g of lithium powder in an argon atmosphere. The vial wassealed with a serum stopper. positioned over a magnetic stirrer, andarranged for continuous flowthrough of argon via two hypodermic needlespiercing the stopper. With argon flowing and stirrer running, toluene (5ml). purified a-methylstyrene (2 ml) and dry tetrahydrofuran (0.6 ml)were introduced successively through another hypodermic needle, whichwas then removed. The contents of the vial were stirred for 30 minutesat room temperature and then allowed to stand for at least 20 minutes topermit excess lithium to float to the surface so that samples of fluidproduct drawn into a syringe through an inserted hypodermic needle wouldbe essentially free of metallic lithium.

Polymerization A dry 250 ml flask containing a magnetic stirring bar andargon under slight positive pressure was loaded with 50 ml of drytoluene and ml (ca 10 g) of isoprene. The isoprene had been previouslypurified and kept under argon by drying regular isoprene over calciumhydride, treating it with butyllithium and allowing heat ofpolymerization to distill excess monomer through a stillhead into a dryreceiver. The mixture in the reaction flask was stirred and heated bymeans of an external water bath at 60C. A 0.6ml quantity of the dilithioamethylstyrene oligomer prepared in Part (a) was injected into theflask, the first 0.2 ml slowly and the remainder rapidly. The heatingbath was removed as soon as the initiator had been added and stirredinto the reaction mixture. Polymerization began very rapidly. asindicated by increase in viscosity. The solution was allowed to stir 45minutes to insure substantially complete polymerization of the isoprene.(A polyisoprene previously prepared in identical fashion was found tohave a number average molecular weight of about 40.000). Step (2)Carboxylation of the Polyisoprene Dry tetrahydrofuran (80 ml) was addedto the dilithiopolyisoprene prepared in step l and the mixture wasstirred to dissolve the viscous polymer. A dry glass inlet tube wasinserted through a side arm of the polymerization flask and carbondioxide was bubbled into the polymer solution for minutes. The solutionbecame more viscous and its yellow color was quickly discharged.Stirring was continued for about 2 hours after the carbon dioxide flowwas stopped. and then an additional 20 ml of tetrahydrofuran was addedto reduce the viscosity of the solution.

Step (3) Tetrabutylammonium Salt of Carboxylated Polyisoprene Thesolution of the dilithium salt of polyisoprene- 0:.w-dicarboxylic acidprepared in Step (2) was treated with 12 g of a 25% solution oftetrabutylammonium hydroxide in methanol. The reaction mixture underwentan immediate marked decrease in viscosity, and it was stirred overnightat C. The reaction mixture was then subjected to three successive steamdistillations by introducing steam through a glass inlet tube. the precipitated polymer in the flask being redissolved twice intetrahydrofuran between steamings. The polymer was next dried bydissolving it in benzene at the boiling point and removing water via theazeotrope with boiling benzene. The residual benzene in the driedsolution was substantially removed under reduced pressure and theresidue was taken up in I ml of dry tetrahydrofuran.

Step (4) Polymerization of Pivalolactone A solution of 4 ml ofpivalolactone in 50 ml of tetrahydrofuran was added with stirring atroom temperature to the solution of tetrabutylammonium salt ofa.w-polyisoprenedicarboxylic acid prepared in Step (3 A gel formed; itwas allowed to stand overnight at room temperature and was thenthoroughly mixed with ethanol containing acetic acid and a small amountof phenylB-naphthylamine antioxidant. The precipitated polymer wasfiltered off and dried in a vacuum oven at approximately C. The driedpolymer weighted 12.9 g (9271 yield, based on 10 g of isoprene and 4 gof pivalolactone used in the preparation). A 7-mil film of the polymer,pressed at 212C under 1000 psi pressure, was strong and clastomeric.

An '8.35-g portion of the above polymerwas refined by extraction forthree days with benzene to remove any isoprene homopolymer. Theundissolved highly swollen polymer was separated from fluid benzenesolution and agitated in a blender with ethanol containingphenyl-B-naphthylamine. The resultant solid was filtered and dried togive 7.2 g of recovered benzeneinsoluble polymer which analyzed for78.80% carbon and 10.42% hydrogen (indicating a block copolymercontaining 33.4% by weight of pivalolactone). A film of the reflnedpolymer. pressed at 215C and 2500 psi pressure. gave strips exhibitingapproximately 20% cold draw. A strip of the film was mechanically drawnto a l007r strain at a rate of 50% per minute and then allowed to relaxfor 18 hours; the strip then showed a tensile strength of 730 psi at abreak elongation of EXAMPLE 2 Pivalolactone/lsoprene/PivalolactoneCopolymer (A) The stepwise procedure of Example 1 was followed asdescribed, except that steps (3) and (4) were altered as follows:

Step (3) Tetrabutylammonium prenedicarboxylic Acid The solution of thedilithium salt of saw-polyisoprenedicarboxylic acid prepared in step (2)was treated with ml of 1M tetrabutylammonium hydroxide in methanol andthe mixture was stirred overnight at room temperature. Most of thesolvent was then removed under reduced pressure and the residue wasmixed with ethanol in a blender to effect precipitation of the polymerin subdivided form. The slightly sticky polymer was separated and workeda second time with fresh ethanol in the blender. The polymer was againseparated, then dissolved in benzene. Benzene. water and ethanol wereremoved from the solution under reduced pressure. The dry residualpolymer was then dissolved in 200 ml of tetrahydrofuran.

Step (4) Formation of Polypivalolactone Pivalolactone (5.5 ml) was addedat room temperature with stirring to the solution of tetrabutylammoniumsalt of polyisoprenedicarboxylic acid prepared in Step (3). A gel formedrapidly. It was allowed to stand overnight at room temperature. was thenmixed thoroughly with 300 ml tetrahydrofuran to facilitate dissolutionof soluble polymer into the non-gel phase. The gel was separated bycentrifugation and mixed thoroughly with ethanol containing acetic acidand phenyl-B-naphthylamine. The polymer thus precipitated was filteredand dried under vacuum at 60C.

The dried polymer (13.2 g, 85% yield) analyzed for 77.49% carbon and10.49% hydrogen. which corresponds to a copolymer containing 37.4% byweight of pivalolactone. A clear film pressed at 215C. and 1500 psipressure was found to cold draw to a white. opaque, strong elastomer.

Salt of Polyiso- EXAMPLE 3 Pivalolactone/lsoprene/PivalolaetoneCopolymer (A) In this example the general procedure of Example 2 wasfollowed, the major change being the use of DiLi-3 (A registeredtrademark of Lithium Corporation of America) as the initiator in step 1l,3-bis( 1-lithio-3- methylpentyl)benzene, made by addition ofsecbutyllithium to m-divinylbenzene.

Step (la) Polyisoprene A reaction flask was placed in a water bath at60C and loaded with a solution of ml (ca 10 g) of isoprene in 50 ml ofcyclohexane, and 0.6 ml of 0.85N initiator was then added. Six minutesafter adding the initiator. polymerization of the isoprene became sovigorous that the heating bath was replaced with an ice bath in order tocontrol the reaction. After 1 hour and 42 minutes, 100 ml of drytetrahydrofuran was added to the very viscous polyisoprene solution.

Step (2) Lithium Salt of Polyisoprenedicarboxylic Acid When thepolyisoprene of step (1) had dissolved in tetrahydrofuran (in about 4minutes), dry carbon dioxide gas was bubbled through the solution for1.5 hours while the flask was cooled in an ice bath. This was followedby bubbling nitrogen through theviscous solution to remove most of theexcess carbon dioxide.

Step (3) Tetrabutylammonium Salt Formation Ten milliliters of 1 molartetrabutylammonium hydroxide in methanol was added to the solution ofpolymerie lithium salt and the resulting low viscosity solution wasstirred overnight at room temperature. Most of the solvent was removedunder reduced pressure and the polymeric tetrabutylammonium salt productwas then precipitated in a blender with ethanol. The polymer wasfiltered. worked a second time in the blender with ethanol. recovered bycentrifuging. and dissolved in hot benzene. The benzene was removedunder reduced pressure. the polymeric salt was dissolved in 200 ml oftetrahydrofuran. and the solution was filtered. Step (4) PivalolactonePolymerization Pivalolactone (5.5 ml) was added at room temperature withstirring to the solution of tetrabutylammonium salt ofpolyisoprenedicarboxylic acid from step (3). A gel formed, was washedwith 600 ml of tetrahydrofuran in a blender. and the resulting fluid wascentrifuged. The gel which separated was added to ethyl alcoholcontaining some acetic acid and phenylfi-naphthylamine to precipitatethe block copolymer. The polymer, after filtering and drying. weighed9.85 g and was found to contain 75.42% carbon and 9.92% hydrogen, whichindicates a copolymer containing 45.7% pivalolactone by weight. A 10 to1 l-mil film of this polymer, pressed at 215C and 5000 psi pressure. hada tensile strengthof 2341 psi at 1214% elongation. A sample of the samefilm was hand-drawn and exercised. after which it had a tensile strengthof 4894 psi at a break elongation of 528%. An x-ray diffraction patternof the exercised film indicated that the polypivalolactone portion wascrystalline but substantially unori ented. A similar film of thepolymer. after being stored for about 3 weeks and then drawn, showed anaverage tensile strength of 3139 psi at 417% elongation at roomtemperature and of 1800 psi at 415% elongation at 100C.

Making of Press-Spun Fibers Additional samples ofpivalolactone/isoprene/ pivalolactone (ABA) block copolymer wereprepared by the procedure of Example 3 with only slight changes: In step(1) 75 m1 of cyclohexane was used, and at the end of step (2) thesolution was centrifuged rather than filtered. Two such products,analyzing for 41.7% and 44.8% pivalolactone, were blended in the amountof 7 and 8 g, respectively, and the blend was molded at 220C and 3000psi pressure to form a plug seven-eighth inch in diameter. Fibers werespun from this plug through a single 15-mil spinneret crifice at210-215C and about 12,000 psi pressure. an exit rate of 12 feet perminute, and a windup rate of 40 feet per minute, thus providing a drawratio of 3.3 during the spinning. The rubbery monofilament showed atenacity of 0.41 g per denier at a break elongation of 345%, and afterheat-setting for 1.5 hours in boiling water it had a tenacity of 0.63 gper denier at a break elongation of 154%. Another sample of the ABApolymer containing 43.9% pivalolactone was pressed into a film at 220Cand 1000 psi pressure; and strips of this film, after being drawn andexercised, showed an average tensile strength of 7570 psi at an averageelongation of 285% In this example the general procedure of Example 3was followed with modifications which allowed all steps to be carriedout in the original reactor-without re moval or isolation of any productexcept the final block copolymer. Step (la) A 250-ml flask equipped witha magnetic stirring bar. a reflux condenser and a gas inlet tube wasloaded with 75 ml of cyclohcxane and 15 ml of purified isoprene underargon. DiLi-3 (0.6 ml. 0.86N) initiator was added and the mixture warmedto 55C for 1 hour during which the isoprene polymerized to give a highlyviscous red-colored solution. The heat was removed and the reactionmixture allowed to come to room temperature for 30 minutes.

Step (2) The reaction mixture was then cooled to C and 100 ml oftetrahydrofuran. previously saturated with dry carbon dioxide uner 4psig pressure, was added. The mixture was allowed to warm to 25C. duringwhich time its red color faded and following some brief initialgellation its viscosity dropped to a fairly low level. Step (3) Afterabout 90 minutes, during which time the homogeneous solution becamecolorless. 0.13 ml of tetramethylethyleneidamine was added and thesolution viscosity dropped further. The solution was then reheated to60C. for 15 minutes and the flask vented with nitrogen to expel excesscarbon dioxide. Tetrabutylammonium hydroxide (0.54 ml. an amountequivalent to the DiLi- 3 used) was added and the mixture kept at about60C. for 0.5 hour. The viscosity of the solution showed a further greatdecrease immediately after adding the tetrabuty'lammonium hydroxide. Thecolor immediately turned to a yellow amber which gradually faded to avery pale amber.

Step (4) After 0.5 hour at 60C.. the solution was cooled to roomtemperature and 5.5 ml of pivalolactone was added. The resultant mixturewas warmed slightly. and in about 15 minutes gelation occurred and itbecame too viscous to stir. it was let stand at room temperatureovernight, and then was mixed with 250 ml of tetrahydrofuran. Themixture was transferred to a blender, and after being blended it wascentrifuged. Extraction with THF showed no homopolyisoprene. The mixturewas finally processed in a blender with about an equal volume of ethanolcontaining acetic acid and'phenyl-B- naphthylamine antioxidant. Theshredded polymer was separated on a filter and dried at room temperatureunder vacuum; yield, 12.5 g (80%, based on starting materials). Analysisby l. R. indicated approximately 45% pivalolactone in the polymer.

Test samples of the polymer were pressed iitto films at 230C. The clearfilms were strong and highly resilient elastomers, but tended to becomeopaque upon being drawn.

EXAMPLE 5 Pivalolaetone/lsoprene/Pivalolactone Copolymer (A) In thisexample the one-pot procedure of Example 4 Cyclohexane. 250 ml:isoprene. 30 ml: DiLi-3. 8.35 X 10 eq. Reaction at 60C. for 40 minutes.then 1 hour at room temperature.v Calculated molecular weight forquantitative reaction: 50.000.

Step (2) Carboxylation.

Tetrahydrofuran solvent. 50 ml: tetrahydrofuran saturated with C0 150ml. Mixture at room temperature for 10 minutes then at 60C. for 1 hour.

Step (3) Salt Transfer.

' Tetrabutylammonium hydroxide. 4.15 X 10" eq. Viscosity and colorchanges were essentially as in Example Step (4) Polypivalolactone.

Pivalolactone. 7.0 ml. was added slowly at 60C. over 3 minutes. Themixture gelled in 7 minutes and cooled to room temperature in one hour.No homopolyisoprene was found upon extraction with THF. This proveschain transfer between Li and NR. since without chain transfer.statistically there would be 25% homopolyisoprene. The product (83.571yield) contained 30% pivalolactone as determined by elemental analysis.Films and fibers were prepared. and were found to be strong. snappy andelastomeric.

EXAM PLE' 6 Pivalolactone/Isoprene/Pivalolactone Copolymer (A) in thisexample the general procedure of Example 5 was followed. except thatpivalolactone was added prior to tetrabutylammonium chloride. which wasused in place of the hydroxide.

The process was carried out in a 500-ml flask and the following detailsare noted.

Step (1a) lsoprene Polymerization.

Cyclohexane. 300 ml. isoprene. 30 ml, DiLi-3. 8.35 X 10" eq.. werecombined and warmed for 40 minutes at 60C. The reaction mixture was thenallowed to come to room temperature in an hour.

Step (2) Carboxylation.

Tetrahydrofuran solvent. 25 ml. and then tetrahydrofuran saturated withC0 ml. were added; the reaction proceeded 5 minutes at room temperatureand then 1 hour at 60C.

Steps (3) and (4) Salt Transfer/Polypivalolactone.

Pivalolactone (7.0 ml) was added at room temperature with no changeinviscosity. Tetrabutylammonium chloride (4.17 X 10 eq.) dissolved intetrahydrofuran was added with a significant decrease in viscosityoccurring on addition. The viscosity began to increase within 4 minutesand a gel formed within 15 minutes. The reaction was allowed to standovernight. The product (84% yield) contained 25.6% pivalolactone asdetermined by elemental analysis and no homopolyisoprene as determinedby extraction with THF. It was readily moldable from a fluid melt into astrong extensible clastomeric film.

EXAMPLE 7 Pivalolactone/lsoprene Copolymer (C) Step (1a) PolyisopreneSubstrate.

Two simultaneous preparations were carried out under argon in 250-mlreactors (A and B) equipped with magnetic-stirrers. reflux condensersand gas inlet tubes. Each flask was charged with 100 ml of eyclohexameand 10 ml (0.1 mole) of isoprene. and then 0.056

ml (6.8 X 10?? mole) of 1.21N sec-butyllithium solution. The mixtureswere stirred at 60C. for 1.5 hours.

Tetramethylethylenediamine (0.1 ml 1.0' mole) was then added andthemixtures kept at 60C for an additional half hour after which theywere vented while at reflux to remove any unpolymerizcd isoprene.

Step 1h) Polylithiation of Substrate.

The monomer-free solutions of monolithiopolyisoprene were treated withadditional 0.224 ml (2.7 X 10 mole) portions of 1.2lN sec-butyllithium.and the reaction was allowed to proceed for 2 hours at 60C. (the totalequivalents of RLi in each reactor'was now 3.38 X 10 moles). The colorof the mixtures slowly turned to deep amber, their viscositiesincreased. and butane was evolved. Periodic observation indicated thatthe butane evolution, color changes and viscosity increases weresubstantially completed within the first hour.

Step (2) Carboxylation of Lithiated Substrate.

Carbon dioxide was bubbled into the reaction mixtures. Stiff gels wereformed. Tetrahydrofuran (50 ml) was added to loosen the gels, theresulting colorless mixtures were kept at 60C. for 30 minutes, and thennitrogen was bubbled through while heating to remove excess carbondioxide. I Step (3) Salt Exchange on Carboxylated Substrate.

ln flask A was placed 0.352 ml (3.38 X 10 mole), i.e, 100% of thelithium equivalent, and in flask B 0.176 ml (1.69 X 10' mole), i.e., 50%of the lithium equivalent, of 25% tetrabutylammonium hydroxide inmethanol. The mixtures were heated to 60C. for minutes and then cooledto room temperature.

Step (4) Polypivalolactone.

Pivalolactone (1.7 ml) was added to each flask, and the mixtures werewarmed briefly and then let stand overnight without stirring. Tight gelswere formed which were macerated with tetrahydrofuran in a blender. Theresulting fluid mixtures were centrifuged and the tetrahydrofuransupernatant portions were removed. The remaining compressed gels werethoroughly mixed with ethanol containing acetic acid andphenyl-B-naphthylamine antioxidant and the precipitated solids werefiltered off and dried under vacuum.

Examination of the final products showed them to be essentiallyidentical. Elemental analysis indicated that both contained about 23%pivalolaetone. Their IR. spectra were identical, and they could bepressed into strong elastomeric films. The films showed elongations inexcess of 150071, very little cold draw, and tensile strengths of 2500psi at break. When heated above 200C. they melted rather sharply andflowed freely. The similarity of products indicated chain transfer hadmade all polypivalolactone segments equivalent.

EXAMPLE 8 Pivalolactone/lsoprene Co mpolymer (C) In this example, thegeneral procedure of Example 7 was followed; the process was run in a500-ml reactor and the following details are noted.

Step (la) lsoprene Polymerization.

Cyclohexane, 250 ml; isoprene, 50 ml; secbutyllithium, 0.3 ml of 1.27Nsolution (3.8 X 10 mole), added slowly; temperature, 50C; time toobservable viscosity increase, 10 minutes; 'tetraethylenediamine, 0.7 ml(6 X 10 mole), added after 1.5 hours. accompanied by significant drop inviscosity and formation of deep yellow colorftotalreaction time, 2hours, followed by venting with argonl Step (lh)Lithiation ofPolyisoprene'subs tr'ate'.'

Sccbutyllithium, 1.5 ml (1.9 X 10 mole) of 1.27N solution added slowly;temperature. 50C: reaction time. 2 hours.

Step (2) Carboxylation ol' Polylithiated Substrate.

Started at room temperature by adding 200 ml of tetrahydrofuranpreviously saturated with carbon dioxide. Initially formed gel broke upand amber color faded with formation of colorless viscous solution. allwithin 10 minutes. The mixture was heated to 50C.: reaction time. 30minutes. Excess CO was removed by venting with nitrogen.

Step (3) Salt Exchange on Carboxylated Substrate.

Tetrabutylammonium hydroxide. 1.2 ml of 25% solution in methanol (9.8 X10" mole) about one-half eq. based on total lithium. was added over 7minutes. The reaction proceeded at 50C. for more minutes. The lowviscosity solution was then'cooled to room temperature.

' Step (4) Polypivalolactone.

Pivalolactone. 11.0 ml. was added slowly at room temperature. A gelformed within about 13 minutes. The mixture was allowed to standovernight to insure completion of the reaction. The precipitated anddried product. in yield, contained 24.971 by weight of pivalolactone. Itwas moldable and melt spinnable into elastic fibers at 250C. Filmsamples were elastomeric with unusually high clongations of 360071 to450071 at break and showed essentially complete recovery after aninitial draw without breaking.

EXAMPLE 9 Pivalolactone/lsoprene Copolymer (B) In this example thegeneral procedure of Examples 7 and 8 were followed, but DiLi-3 was usedinstead of sec-butyllithium as initiator in the formation of thepolyisoprene substrate.

Step (la) lsoprene Polymerization.

Cyclohexane, 300 ml; isoprene, 30 ml (20.4 g. 0.3 mole); DiLi-3. 0.93N,0.5 ml (4.65 X 10 eq.); temperature, 60C; time, 1.5 hours.

Step (1b) Lithiation of Polyisoprene.

Tetramethylethylenediamine, 0.55 ml (3.82 X 10 mole); temperature,60C;sec-buty1lithium, 1.27N, 1.0 ml (1.27 X 10" eq.), added slowly after20 minutes at 60C; total time, 2.33 hours.

Step (2) Carboxylation of Lithiated Polyisoprene.

At room temperature, tetrahydrofuran (25 ml) followed by tetrahydrofuranpreviously saturated with C0 ml); heated to 60C; reaction time at 60C,0.5 hour.

Step (3) Salt Exchange on Carboxylated Substrate.

Tetrabutylammonium hydroxide. 1.04 ml (8.35 X 10 mole); temperature,60C; time, 0.5 hour.

Step (4) Polypivalolactone.

Pivalolactone, 8.6 g in 25 ml of tetrahydrofuran, was added at roomtemperature and reacted overnight. The elastomeric product, 24.4 g(84.0% yield), contained 33.7% pivalolactone by elemental analysis.

EXAMPLE l0 Pivalolactone/lsoprene Copolymer (B) ln this example thegeneral procedure of Example 9 was followed except thattetrabutylammonium chloride was used instead of tetrabutylammoniumhydroxide in the salt (ion) exchange step on the carboxylated substrate.The following details are noted.

Step (la) lsoprene Polymerizationv Cyclohexane. 300 ml; isoprene. 30 ml(20.4 g. 0.3 mole): DiLi-3. 0.93N. 0.9 ml (8.38 X 10 eq.); temperature.60C; time. 1.5 hours.

Step lb) Lithiation of Polyisoprene.

Tetramethylenediamine. 0.7 ml (4.8 X 10 eq.); temperature. 60C;secbutyllithium. 1.27N, 1.0 ml 1.27 X 10" cq.), added after minutes at60C; total time. 2.33 hours.

Steps (2) and (3) Carhoxylation/Salt Exchange.

Room temperature; added 150 ml Co -saturated tetrahydrofuran containing0.39 g (1.4 X l0eq) tetrabutylammonium chloride; time. 1 hour.

Step (4) Polypivalolacetonc.

Pivalolactone. 8.6 ml in ml of tetrahydrofuran, was added at roomtemperature and reacted overnight. The elastomeric product, 23.0 g (80%yield). contained 37.4% pivalolactone.

The copolymer obtained in this example was an outstanding moldable andspinnable elastomer. A 200- denier filament was spun at 264C. through asingle hole 15 mil spinneret from a inch plug under 500 psi. Thecopolymer was remolded several times without loss of properties. Infact. both fibers and film gained in tensile strength upon working.Working included initial cold drawing after which the copolymersrecovered substantially completely.

EXAMPLE 11 Pivalolactone/lsoprene Copolymer (B) Step 1(a) PolyisoprenePreparation of the 1,3-Bis( llithio-l,3-dimethylpentyl)-benzeneinitiator A dry quart bottle is flushed with argon and stoppered with arubber septum through which an argon breather tube is inserted. 440 mlof sodium-dried cyclo hexane, 21 ml 150 meq.) of twice distilled andbutyllithium-dried triethylamine, and 38.4 ml (50 meq) of 1.3 Ns-butyllithium is placed in this bottle. To this mixture is slowly added4.34 ml (50 meq) of freshly distilled. butyllithium-driedm-diisopropenylbenzene. The reaction mixture is held for l-2 hours atroom temperature. the breather tube removed, and the resulting 0.1 Nsolution then placed in a refrigerated drybox until ready for use.Normally the catalyst ages for a couple of days to insure completereaction of the diisopropenyl compound with butyllithium.

Polymerization A flame-dried 2-liter reactor is fitted with a sealedtop, a T-tube for maintaining a dry argon atmosphere, a vibromixerstirrer, and a septum-stoppered inlet port. Into this reactor are placed900 ml of sodium-dried cyelohexane and 120 ml (80 g) ofbutyllithium-dried isoprene. The mixture is heated to 50C. and chargedwith 64 ml of the above 0.1 N l,3-bis( l-lithio-l,3-dimethylpentyl)benzene initiator solution. The reaction mixturereaches 56C., the heating bath is removed and a cooling bath applied inorder to maintain the temperature at about 52C. After 47 minutes and thesubsidence of the reaction, a further application of the heating bathmaintain the reactor temperature at 53C. The reaction proceeds for 2hours, during which time essentially all the isoprene reacts. At thistime the reaction mixture is highly viscous due to association of thelithiated chain ends of the a,w-dilithiopolyisoprene. The small amountof triethylamine present enhances the reaction rate but has no adverseeffect on the polydiene microstructure which appears to be greater than90 percent in the total 1.4-content.

After the completion of the diene polymerization. 0.50 ml oftetramethylethylenediamine (TMEDA). distilled from a mixture withmetallic sodium. is added to the reaction mixture. The viscosityimmediately drops as the lithium groups dissociate through complexingwith the TMEDA. The color also changes from a very pale ginger to deepyellow. The reaction proceeds for an additional 10 minutes to allow theconsumption of any residual isoprene monomer by the activated polymericdianions.

Step 1(1)) Lithiation of Polyisoprene A mixture of 35 ml of drycyclohexane. 2.7 ml of TMEDA and 5.2 ml of 1.45 N n-butyllithium is thenadded to the reaction mixture to effect metallation of the polymerbackbone. The mixture, stirred for 1 hour at 53C.. gives a clear, deepamber. polydienepolyanionic solution. The reaction then cools to 25C. inpreparation for transfer to a carbon dioxide-saturated THF solution.

Step 2 Carboxylation of Lithiated Polyisoprene In a second 2-literreactor is placed 900 ml of sodium-dried THF saturated with carbondioxide. The polydienepolycarbanion solution is then transferred fromthe first to the second reactor through a glass transfer tube bypressurizing the first reactor with ar gon, with vigorous stirringduring the transfer to maximize contact of carbanions with excess carbondioxide and thus prevent crosslinking by ketone formation. Excess carbondioxide is removed from the resulting clear. colorless viscous solutionby mild evacuation and vigorous stirring. Finally, additional THF isadded to further reduce the viscosity of the polymer mixture, nowweighing 1658 gm.

Step 3 Salt Exchange on Carboxylated Substrate A 196 gm. portion of theabove solution, containing 9.4 gm. of polyisoprene with 1.65 meq. oflithium carboxylate is transferred to a third reactor. To this is added2.3 ml of 0.36 N tetrabutylammonium chloride in THF (0.83 meq); and themixture stirred for 23 minutes to allow for the establishment ofequilibrium. Step 4 Polypivalolaetone 8.7 gm. of the pivalolactonemonomer is dissolved in 25 ml of THF and slowly added to the polymersolution. The mixture is stirred at room temperature for 28 minutes, atwhich time gelation occurs. The gelled reaction mixture, after sittingovernight, is blended with an additional 225 ml of THF and thenprecipitated by adding 400 ml of 28 ethanol. The polymer is filtered.washed three times with 50 ml aliquots of ethanol, and then swollen with50 ml of benzene containing 90 mg. of phenyl B-naphthylamineantioxidant. A vacuum at C. removes the benzene and yields a 17 gm.sample of block graft polymer. The calculated composition of this sampleis:

a. 25.000 g/m polyisoprene molecular weight,

b. 3.7 total carboxylate graft sites including ends,

c. 48% pivalolactone, each segment having a degree of polymerization(DP) of 53. The melted polymer displays high fluidity.

Preparation of Elastomeric Fiber The above polymer is molded into a inchdiameter plug at 200C. and spun from this in a 2 inches long pressspinneret having a 20 mil orifice. with a hot zone maintained at 276C.The extruded fiber is exercised by successive drawing and relaxation todevelop optimum strength. Testing for tensile strength and elongationwith lnstron and Suter testing machines give the results below.Differences in ultimate test values probably derive from differences injaw design and testing technique.

Fiber Test Data Tensile at break 0.47 gld lnstron 0.78 gld Sutcr testor5 Elongation at break 2667! lnstron 340% Sutcr testor Load Power at 5071elongation 42 mg/ed Load Power at 90'71 elongation 84 mg/ed Unload Powerat 50% elongation 27 mg/cd Unload Power at 90% elongation 70 mg/edPermanent set 8.571.

Tables 1 and 2 and Discussion of Copolymer Properties All of the novelcopolymers are readily injection moldable and melt spinnable attemperatures of about 250C. to 275C. As will be seen from Tables 1 and 2that follow, the novel copolymers are characterized by good elongationproperties, high tensile strengths and by high melt indices attemperatures of 250C. and above. it has been found that there is littleor no flow at temperatures of 200C. and below. In fact, itjs especiallycharacteristic of the novel copolymers, regarding melt flow properties,that they have a melt index of essentially zero at about 180C. andbelow, and a melt index of at least 2.0 at 250C. and above (ASTM Dl23857T).

The novel copolymers are also-characterized by moderately narrowmolecular weight ranges originating in the polydiene substrate. 1t hasbeen found that they have dispersities between about 1.0 to 2.0. Thesedesirable molecular weight distributions influence melt viscosity andtensile strength properties. See. F. W. Billmeyer. Textbook of PolymerScience. lnterscience Publishers, 1966, pps. 208-211; and. J. Brandrupet al., Polymer Handbook, Chapter VI-50; J. F. Rudd, J. Poly. Sci. 44.459-470 (1960).

Dispersities determined for the copolymers made by the procedures of theExamples are as follows: Examples l to 3. between 1.3 to 1.6; Examples4-6 and 910. between 1.6 to 1.7; Examples 78. between 1.0 to 1.3.

It is a most interesting facet of this invention that excrcisingcopolymer fibers and films. e.g.. cold-drawing. pulling. kneading. etc.,increases the tensile. strength thereof. As can-be seen from Table 2.all copolymer samples exhibit very high elongation properties. 1t canalso be seen that already good tensile strengths are greatly improved byexercising, defined as working specifically by successively drawing andrelaxing the fibers and films. Furthermore. and surprisingly. exercisedand strengthened elastomers retain stretchability and snap- 'backproperties.

Without wishing to be bound by this explanation, it is hypothesized thatexercising increases tensile strength by causing molecular orientationof the polydiene segments as well as of the polypivalolactone segments.Exercised fibers. filaments, films or articles of manufacture such asmolded. pressed or spun articles 30 are included within the scope ofthis invention.

TABLE 1 Properties of Copolymers Having Polyisoprene Block ofApproximately 50,000 M.W.

Sample Copolymer Wt. Tested at Tensile strength Elong. at

No. Type PVL Form C. psi or g/d break Melt Index 7 Temp C. Rate of flow(g/10 min.) 1 (A) 43.9 film 25 7570 285 i 2 (A) 45.7 film 25 3050 415 3(A) 45.7 film 100 1800 415 250 5.3 4 (A) 28.5 250 8.0 5 (A) 28.5 200 0 6(8) 46.5 260 34 "Made in accordance with the novel process of thisinvention for the particular type of copolymer. i.e.. (A) or (B). "'ASTMtest No. D |23857T. A11 polymers preheated approximately 1 hr. atindicated temperature prior to making test.

"Samples 2 and 3 were from the same copolymer. that of Example 3. "Samecopolymer as Sample 4. Calculated to have 3 polypivalolactone-containingsidechains.

Table 2 Properties of Copolymers Having the Indicated PolyisopreneMolecular Weights Equiv. of Copotetraalkyl- Press temp Tensile lymerM.W. of ammonium Degree of or spinstrength Sample type/ polyiso- No. ofPVL salt based polymerining temp psi or elong. at

No. Ex. No. prene (M,,) sidechains on total Li PVL zation PVL Form C.g/d break Remarks 7 (C 8 100,000 5 0.43 24.9 48 film 260 1645 4800unexercised 8 same film 260 5 100 3200 exercised 9 same fiber 2500.24g/d 946 drawn and heat set 10 same fiber 250 0.15g/d 2335 as spun 11 (C) 100,000 5 0.43 24 48 film 250 2700 4200 unexercised 12 (A) 50.000none 0.50 27 84 film 260 1440 4600 unexercised 13 same film 260 46502700 exercised 14 (A) 20.000 none 0.43 41 6O film 270 450 500unexercised l5 (AIS film 260 1330 4600 unexercised 16 same film 260 26202600 predrawn 1 cycle 17 (A )/6 50.000 none 0.5 28 90 film 260 1080 4100unexercised pressed on 18 same film 260 850 3800 unexercised pressed onTeflon Table 2-Continued I Properties of Copolymers"-" Having theIndicated Polyisoprene Molecular Wcights Equivi of Copotctraalkyl- Presstemp Tensile ly mer M.W. of ammonium Degree of or spinstrength Sampletype/ polyiso- No. of PVL 3 salt based 7? polymerining temp psi orelong. at

No. Ex. No. prene (M,,) sidechains on total Li PVL zation PVL Form C.g/d break 7! Remarks l9 same film 260 1770 3300 exercised 20 (8)1990,000 3 0.5 33.7 53 film 280 5 I 2600 exercised 2i (C) 100,000 0.5 2644 film 260 5350 l800 exercised 22 (B)/l0 50,000 3 0.5 37.4 film 2702600 2600 unexercised 23 same film 270 H000 I500 exercised 24 same film270 (9000- (1200- exercised 15000) I500) 25 same fibers 265 0.47 700exercised 26 same fibers 265 0.5-0.8 600- exercised "l'ensile andelongation measurements were made both on a Scott Rubber Tensile Testerwith a crosshcadspee'd of 66007dmin. and on an lnstron Tester at 400%/min.

Results agree.

*Made in accordance with the novel process of this invention for theparticular type of copolymei-i iie. (A), (B) or (C)v The embodiments ofthe invention in which an exclusive property or privilege is claimed aredefined as follows:

l. A copolymer derived from pivalolactonc and a diene selectedfromisoprene and butadienc.

vary between about 1300 to l 700,000 said copolymer being furthercharacterized by having a melt'iridcx of zero alt C. and at least 2.0 at250"Cv 2. A copolymer according to claim 1, wherein l and k are between15 to 200. in is between I00 to 5.000 and .\"is between 1' to 50L V i v3. A copolymer according to claim 1 wherein the cliche unit is isoprcne.

4. A copolymer according to claim 1, wherein the diene unit isbutadiene.

5. An exercised copolymer according to claim 1.

6. A process for making the copolymer of claim 1, comprising exercisingthe .copolymer of claim 1.

7. An article of manufacture comprising the copolymer of claim 1. I I f8. An article according to claim'7 in the form of a fiber. i

9. An article according to claim 7 in the form of a film. 1 g

10. An article according to claim 7 in the form of a molded object.

UNITED STATES PATENT OFFICE Page 1 of 2 CERTIFICATE OF CORRECTION PATENTNO. 3,907,933

DATED September 2 3, 1975 INVENTOR(S) Robert Paul Foss It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 21, the formula should read t cH -c': c=0

CH2-O Column 2,

(pivalolactone) Column 3, line 13,

copolymer C-.

Column 5, line 6, "when" Column 6, line 65, "combin" Column line 5, theformula should read eneT CO--tpivalolactone) "copolymer (2" should readshould read When--.

should read combine-.

8, line 44, "phenylB" should read --phenyl8 .v 'Page 2 Of 2 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Q PATENT NO. 3,907,933

DATED I September 23, 1975 INVENTOR(S) Robert Paul Foss It is certifiedthat error appears in the ab0vetdentified patent and that said LettersPatent are hereby corrected as shown below:

Column 10, line 50, "orifice" should read -orifice.

Column 12, line 2, "l0 should read --l0' Column 15, line 12, "10'"should read --l0' Column 16, line 64, "3/4" should read 7/8-.

Column 17, line 9, "5 Elongation" should read -Elongation-. 0

Column 20, Claim 6, line 1, "Claim 1'' should read Claim 5.

Signed and Sealed this second D3) of March 1976 [SEAL] G Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'Patenlsand Trademarks

1. A COPOLYMER DERIVED FROM PIVALOLACTONE AND A DIENE SELECTED FROMISOPRENE AND BUTADIENE,
 2. A copolymer according to claim 1, wherein 1and k are between 15 to 200, m is between 100 to 5,000 and x is between1 to
 50. 3. A copolymer according to claim 1 wherein the diene unit isisoprene.
 4. A copolymer according to claim 1, wherein the diene unit isbutadiene.
 5. An exercised copolymer according to claim
 1. 6. A processfor making the copolymer of claim 1, comprising exercising the copolymerof claim
 1. 7. An article of manufacture comprising the copolymer ofclaim
 8. An article according to claim 7 in the form of a fiber.
 9. Anarticle according to claim 7 in the form of a film.
 10. An articleaccording to claim 7 in the form of a molded object.